HAL Mines Nantes
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    7022 research outputs found

    Multi-Calorimetry in Light-based Neutrino Detectors

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    International audienceNeutrino detectors are among the largest photonics instruments built for fundamental research. Since its inception, neutrino detection has been inexorably linked to the challenging detection of scarce photons in huge instrumented volumes. Many discoveries in neutrino physics, including the neutrino itself, are inseparable from the evolution of the detector photonics interfaces, i.e. photo-sensors and readout electronics, to yield ever higher precision and richer detection information. The measurement of the energy of neutrinos, referred to as calorimetry, is pursued today to reach permille level systematics control precision, thus leading to further innovation in specialised photonics. This publication describes a novel articulation that detectors may be endowed with multiple photonics interfaces for simultaneous light detection to yield unprecedented high-precision calorimetry. This multi-calorimetry approach opens the novel notion of dual-calorimetry detectors as an evolution from the single-calorimetry setups used over several decades for most experiments so far. The dual-calorimetry design exploits unique response synergies between photon counting and photon-integration detection systems, including correlations and cancellations between calorimetric responses, to yield the unprecedented mitigation of the dominant response systematic effects today for the possible improved design of a new generation of neutrino experiments

    Semi-inclusive single-jet production in DIS at next-to-leading order in the Color Glass Condensate

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    International audienceWithin the Color Glass Condensate (CGC) effective field theory, we derive the next-to-leading order (NLO) cross-section for the single-jet semi-inclusive cross-section in deep inelastic scattering (DIS) at small xx, for both longitudinally and transversely polarized virtual photons. We provide analytic expressions, valid at finite NcN_c and suitable for numerical evaluation, for both the cross-section differential in rapidity and transverse momentum and the cross-section differential in rapidity only. Our NLO formulae demonstrate that the very forward rapidity regime is plagued by large double logarithmic corrections coming from phase space constraints on soft gluons close to the kinematic threshold for jet production. A joint resummation of small-xx and threshold logarithms at single logarithmic accuracy is proposed to remedy the instability of the cross-section in this regime. By integrating over the single-jet phase space, we recover known results for the NLO DIS structure functions at small xx, previously obtained using the optical theorem

    Charged-particle production as a function of the relative transverse activity classifier in pp, p-Pb, and Pb-Pb collisions at the LHC

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    International audienceMeasurements of charged-particle production in pp, p-Pb, and Pb-Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum (pTtrigp_{\mathrm{T}}^{\rm trig}) in the range 8<pTtrig<158<p_{\mathrm{T}}^{\rm trig}<15 GeV/c/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, RT=NchT/NchTR_{\mathrm{T}}=N_{\mathrm{ch}}^{\mathrm{T}}/\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle, is used to group events according to their UE activity, where NchTN_{\mathrm{ch}}^{\mathrm{T}} is the charged-particle multiplicity per event in the transverse region and NchT\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle is the mean value over the whole analysed sample. The energy dependence of the RTR_{\mathrm{T}} distributions in pp collisions at s=2.76\sqrt{s}=2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particle pTp_{\rm T} spectra as a function of RTR_{\mathrm{T}} in the three azimuthal regions in pp, p-Pb, and Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p-Pb)

    Advancing the understanding of energy-energy correlators in heavy-ion collisions

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    International audienceWe investigate the collinear limit of the energy-energy correlator (EEC) in a heavy-ion context. First, we revisit the leading-logarithmic (LL) resummation of this observable in vacuum following a diagrammatic approach. We argue that this route allows to naturally incorporate medium-induced effects into the all-orders structure systematically. As an example, we show how the phase-space constraints imposed by the medium on vacuum-like emissions can be incorporated into the LL result by modifying the anomalous dimensions. On the fixed-order side, we calculate the O(αs)\mathcal{O}(\alpha_s) expansion of the in-medium EEC for a γqqˉ\gamma\to q\bar q splitting using, for the first time, the exact matrix element. When comparing this result to previously used approximations in the literature, we find up to O(1)\mathcal{O}(1) deviations in the regime of interest for jet quenching signatures. Energy loss effects are also quantified and further suppress the EEC at large angles. These semi-analytic studies are complemented with a phenomenological study using the jet quenching Monte Carlo JetMed. Finally, we argue that the imprint of medium-induced effects in energy-energy correlators can be enhanced by using an alternative definition that takes as input Lund primary declusterings instead of particles

    Investigating the nature of the K0(700)^*_0(700) state with π±\pi^\pmKS0^0_{\rm S} correlations at the LHC

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    International audienceThe first measurements of femtoscopic correlations with the particle pair combinations π±\pi^\pmKS0^0_{\rm S} in pp collisions at s=13\sqrt{s}=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0(700)^*_0(700) particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a π±\pi^\pmKS0^0_{\rm S} pair. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0(700)^*_0(700). The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K0(700)^*_0(700) is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0(700)^*_0(700) resonance

    New Constraint for Isotropic Lorentz Violation from LHC Data

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    International audienceNew calculations for the kinematics of photon decay to fermions in vacuo under an isotropic violation of Lorentz invariance (LV), parameterized by the Standard-Model Extension (SME), are presented in this paper and used to interpret prompt photon production in LHC data. The measurement of inclusive prompt photon production at the LHC Run 2, with photons observed up to a transverse energy of 2.5 TeV, provides the lower bound κ~tr>1.06×1013\tilde{\kappa}_{\mathrm{tr}} > -1.06 \times 10^{-13} on the isotropic coefficient κ~tr\tilde{\kappa}_{\mathrm{tr}} at 95% confidence level. This result improves over the previous bound from hadron colliders by a factor of 55. The calculations for the kinematics of photon decay have further potential use to constrain LV coefficients from the appearance of fermion pairs, for instance, top-antitop

    The force-force correlator at the hard thermal scale of hot QCD

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    International audienceHigh-energy particles traversing the Quark-Gluon plasma experience modified (massive) dispersion, although their vacuum mass is negligible compared to the kinetic energy. Due to poor convergence of the perturbative series in the regime of soft loop momenta, a more precise determination of this effective mass is needed. This paper continues our investigation on the factorisation between strongly-coupled infrared classical and perturbative ultraviolet behavior. The former has been studied non-perturbatively within EQCD by determining a non-local operator on the lattice. By computing the temperature-scale contribution to the same operator in 4D QCD at next-to-leading order (NLO), we remove the ultraviolet divergence of the EQCD calculation with an opposite infrared divergence from the hard thermal scale. The result is a consistent, regulator-independent determination of the classical contribution where the emergence of new divergences signals sensitivities to new regions of phase space. We address the numerical impact of the classical and NLO thermal corrections on the convergence of the factorised approach and on the partial applicability of our results to calculations of transport coefficients

    EUSO-SPB1 mission and science

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    International audienceThe Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33 km). After 12 days and 4 h aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of ⪆3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search

    Coherent gluon radiation: beyond leading-log accuracy

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    International audienceResults are presented for the medium-induced, soft coherent radiation spectrum for all 222\to 2 partonic channels in QCD, at leading-order in αs\alpha_s but beyond leading logarithmic accuracy. The general formula is valid in the full kinematic range of the underlying process, and reduces to previous results in special cases. The soft gluon radiation spectrum is expressed in terms of the color density matrix specific to each channel, quantifying the entanglement between the color components of the 222 \to 2 production amplitude. Beyond the leading logarithm, the spectrum depends explicitly on the off-diagonal elements of this matrix, owing to the soft gluon's ability to probe the internal color structure of the parton pair

    Dense nuclear matter equation of state from heavy-ion collisions

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    International audienceThe nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS

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    HAL Mines Nantes is based in France
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